1. Technical Field
This invention relates to a method of measuring the metal carbonyl content of fluid streams, e.g., syngas or coal gasification process streams, carbon monoxide gas, air, and liquid solutions. The method is useful in detecting and measuring the metal carbonyl content of such streams in parts per billion (ppb).
It is known that some metal carbonyls, particularly iron pentacarbonyl (Fe(CO).sub.5) and nickel tetracarbonyl (Ni(CO).sub.4), act as catalyst poisons in some processes. In others they can react with hydrogen sulfide to form deposits of nickel and iron sulfides thus fouling process equipment. In view of these problems it is advantageous to run processes to minimize the formation of these carbonyls. However, in order to do so, an accurate method for their measurement is required.
U.S. Pat. No. 4,108,552 describes a method for such measurement. In this method a gaseous sample is fed into two separate gas chromatograph columns, one column separates iron pentacarbonyl and the other column separates nickel tetracarbonyl. After separation both carbonyls are detected and measured by flame photometry.
2. Summary of the Invention
The applicant has discovered an improved method of measuring such metal carbonyls.
In this method, first a representative fluid sample is obtained. Then the sample is fed with carrier gas into an on-column glass column in a gas chromatograph. This column operates at 23-40.degree. C., preferably about 31.degree. C., and simultaneously separates the individual metal carbonyls from the sample. Squalane is employed as the stationary liquid phase for the separation. The stream from the gas chromatographic column is then fed into a constant current, electron capture detector where the metal carbonyl content is detected and a signal produced.
The process of the invention has the advantages that the determination and measurement of metal carbonyls can be accomplished quickly, less then ten minutes, and accurately with a lower detection limit of less than one ppb. With such rapid, accurate and sensitive response, the process can be tied into the process involved for control of the reaction to avoid metal carbonyl production. It can also be used to provide a quick reading of the environment for determining worker exposure to the carbonyls.